So I put craftbukkit through a VM to see if anything "bad" is happening during normal server use. This is what I found: As the server normally starts up there is about 3,000 classes loaded. After one reload is jumps to about 3,700 classes and a second reload is 4,200 classes. Same thing with the threads, starts at 25, first reload 30 and second reload 35. So I left the server running for about 30 mins and none of the classes were uploaded and the threads stayed around 31. I am bringing this up because every time you reload the server more and more classes get loaded and none of them are unloaded. Same thing with threads. Most of these loaded classes are from plugins so it shouldn't be to hard to unload the plugin when you reload the server. Yes it "stops" the plugin then starts it again but the old classes stay in memory.